In recent years, a power storage battery is going large, studied so as to be used for: driving of electric vehicles such as an electric car, an electric bike and the like; and storing power that is consumed in households, stores, buildings and the like, and is expected to be widespread in the future. Besides, from the viewpoint of reduction in emission amount of carbon dioxide and the like, an electric vehicle is desired to be widespread.
For the spread of an electric vehicle, the spread of a charge system, which charges a power storage battery (hereinafter, called a battery) for driving an electric vehicle, is inevitable. Especially, the spread of a charge system, which charges a battery of an electric vehicle outside a household, is inevitable. Regarding this, a plan is proposed so as to dispose a charge system at stores such as a convenience store and the like.
In a case where a charge system is disposed at a store and the like, besides power that is consumed by various apparatuses such as an illumination device, an air conditioner, a refrigerator and the like, it is also necessary for the store and the like to supply power that is consumed by the charge system. The power consumed by a charge system is likely to be equal in amount to (e.g., substantially equal to each other in the order of power) the power consumed by various apparatuses in a store and the like. Because of this, the power amount which a store and the like purchase from an electric power company increases, which becomes a problem that the power rate increases, and the problem is likely to become a cause that discourages the spread of a charge system.
Accordingly, for example, a patent document 1 proposes a charge system, which preferentially uses a time zone where a unit power rate is inexpensive and a time zone where power is in less demand, thereby reducing the power rate.